Bistable electromagnetic valve

ABSTRACT

A bistable electromagnetic valve is proposed, which is to be used in refrigerant circuits. The valve can be produced at particularly low outlay and at the same time is reliably leaktight. This is achieved, according to the invention, in that the valve chamber ( 7 ) is formed within a control coil ( 3 ) by a cylindrical tubular body ( 2 ) which extends at least beyond the pole pieces ( 5, 6 ) inserted into the cylindrical tubular body ( 2 ).

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The invention relates to a bistable electromagnetic valvecharacterized by a valve chamber (7) arranged within a control coil (3)and the outer wall of the valve chamber (7) that is formed within thecontrol coil (3) by a cylindrical tubular body (2) which extends atleast beyond the pole pieces (5,6) inserted into the cylindrical tubularbody (2).

[0003] 2. Description of the Related Art Including Information DisclosedUnder 37 C.F.R. 1.97 And 1.98

[0004] Prior art valves of this type are used, for example, inrefrigerant circuits, such as are described in the publications DE 37 18490 or BP 10 54 200.

[0005] In such valves, a bistable situation is achieved by permanentmagnets being arranged outside the valve housing, next to the valvechamber or next to the pole pieces, so that the valve body has, at thepole pieces, two end positions in which it is held by these permanentmagnets.

[0006] High requirements in terms of leaktightness and long-termstability are placed on such valves. Furthermore, as is customary, thereis the requirement to produce such a valve as cost-effectively aspossible.

BRIEF SUMMARY OF THE INVENTION

[0007] The object of the invention is, therefore, to propose a valvewhich can be produced at little outlay and is reliably leaktight.

[0008] This object is achieved, starting from a valve for a refrigerantcircuit of the type mentioned in the field of the inventioncharacterized by a valve chamber (7) arranged within a coil (3) and theouter wall of the valve chamber (7) that is formed within the coil (3)by a cylindrical tubular body (2) which extends at least beyond the polepieces (5,6) inserted into the cylindrical tubular body (2).

[0009] Advantageous designs and developments of the invention arepossible as a result of the features described in the followingdescription of the invention including drawings and dependent claims.

[0010] Accordingly, a valve according to the invention is distinguishedin that the valve chamber is arranged within the control coil and theouter wall of the valve chamber within the control coil is formed by acylindrical tubular body. The tubular body in this case extends at leastbeyond the pole pieces inserted into the cylindrical tubular body.

[0011] This means that, in contrast to conventional valves, the polepieces do not have the connections, but, instead, the latter are simplyintroduced into the tubular body. Leaktightness problems between thetubular body and the pole pieces are consequently prevented completelyat the lowest possible outlay.

[0012] In a development of the invention, the tubular body is designedto be of a length such that it extends at least as far as the end facesof the control coil. Thus, even with the control coil put in place, thetubular body is easily accessible. Moreover, the tubular body can beadapted to the inside diameter of the coil, without connection pointshaving to be taken into account.

[0013] Furthermore, in this case, fluid connections of the valve can beattached in a particularly simple way to the cylindrical tubular bodyaccessible outside the control coil.

[0014] A particularly simple design of such a fluid connection arises inthat at least one end of the tubular body is used as a tubularconnection for the fluid. In addition to a minimal number of sealingpoints, this, in turn, affords the advantage of extremely favorablemanufacture, since the tubular connection is formed in the simplestinstance by one end of the cylindrical tubular body which is alreadypresent in any case.

[0015] Preferably, further valve components are inserted into thetubular body. Those which come under consideration in this case are, forexample, the permanent magnets necessary for bistable functioning orelse filter elements in order to filter dirt particles or, in general,impurities out of the fluid. In principle, however, further valvecomponents may also be integrated readily into the cylindrical tubularbody.

[0016] Dirt filters, which may be designed, for example, as a sieve tubeor else as a magnetic filter element for the separation of magnetic ormagnetizable particles, keep impurities away from the valve body and thevalve seat, so that the wear of these components is effectively reduced.This results, in turn, in a high long-term stability of the valve. It ispointed out particularly, at the same time, that such valves are usedconventionally in closed fluid circuits, so that the filter capacity hasto be sufficient merely for once-only purification of the fluid volumelocated in the circuit.

[0017] Moreover, it is advantageous to fix at least one of the saidvalve components to the inside of the tubular body at least in the axialdirection. The valve thereby forms a unit capable of being handled inthe unconnected state, without the possibility of any valve componentsfalling out of the cylindrical tubular body on the end face.

[0018] Axial fixing can be achieved, for example, by the correspondingvalve component being pressed together with the tubular body inside thelatter. Such pressing can be implemented at little outlay, for example,by pressure on the tubular body from outside, and, in particular, even aplurality of valve components can be fixed in one operation.Furthermore, by pressing, a valve component can also be fixed reliablyin the radial direction.

[0019] In a simple embodiment, even a peripheral bead or a nose pressedin on the outside may be sufficient for axial fixing. Thus, for example,all the valve components may be designed in such a way that they have ineach case an abutment against one another, so that, by a bead or a nosebeing applied on both sides, the complete valve unit pushed into thetubular body is both fixed in the tubular body and secured againstrelative displacement by the mutual abutments.

[0020] In a further advantageous embodiment, an additional inner tube ispushed into the tubular body at least on one side of the valve chamber.What is known as a 3/2-way valve can also be produced in this way. Thespace between the inner tube and the cylindrical tubular bodyaccordingly serves as an inflow line, in which case a duct to the innervalve chamber must be formed on or in the corresponding pole piece. Inthe simplest instance, such a duct may be formed by a circumferentialrecess on the pole piece. The inner tube itself then forms an outflowfor the fluid in one switching position of the valve body. In the otherswitching position, the opposite end of the tubular body can be used asan outflow.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] An exemplary embodiment of the invention is illustrated in thedrawing and is explained in more detail below with reference to thefigures of which, in particular,

[0022]FIG. 1 shows a cross section through a 2/2-way valve according tothe invention, and

[0023]FIG. 2 shows a cross section through a 3/2-way valve according tothe invention.

DETAILED DESCRIPTION OF THE INVENTION

[0024] The valve 1 according to FIG. 1 comprises a cylindrical tubularbody 2 according to the invention as a valve housing which passescompletely through a control coil 3. Adapter pieces 4 in this caseensure a good fit in the valve housing 2 and are designed at the sametime as flux guide elements for an increased magnetic flux through polepieces 5, 6 and through a valve chamber 7. Inside the valve chamber 7 islocated a spherical valve body 8 which, in the position illustrated,lies on the spherical seat 9 of the pole piece 6 and at the same timecloses a passage bore 10. The passage bore 10 issues into the outflowline 11 of the valve 1.

[0025] The tubular body 2 extends into the space outside the coil 3 andtherefore also beyond the pole pieces 5, 6.

[0026] Annular magnets 12, 13 lying outside the tubular body 2 ensurethe bistable behavior of the valve and are fixed by means of a spacerring 14 between the adapter pieces 4.

[0027] The pole piece 5 has in its outer circumference recesses orflattenings which produce fluid ducts 15 between the pole piece 5 andthe tubular body 2 into the inside of the valve chamber 7. The fluidducts could also be implemented by bores in the pole piece 5, theinflow-side orifices of said bores lying in the annular region between atubular sieve 18 and the outer wall of the tubular body 2. The polepiece 5 has, furthermore, a spherical seat 16, in order to bring about adefined end position of the valve body 8 in the second end position, notillustrated.

[0028] The pole piece 5 comprises a step 17, onto which the tubularsieve 18 is pushed. At the opposite end, the tubular sieve 18 is fixedin a magnetic filter 19 designed as an annular magnet. The tubularregion of the tubular body 2 in which the tubular sieve 18 and themagnetic filter 19 are located serves as an inflow line 20 for thecorresponding fluid, that is to say, in particular, for refrigerant.

[0029] Inflowing fluid (see arrow P) passes first into the region of themagnetic filter 19, which is designed as an annular magnet, and comesdirectly into contact with the fluid. As a result, magnetic ormagnetizable dirt particles are already fixed permanently to themagnetic filter 19 at a considerable distance from the valve chamber 7.

[0030] The fluid subsequently passes into the inside of the tubularsieve 18 which is closed on the end face, at the opposite end, by thepole piece 5 or its step 17. The fluid flow accordingly has to takeplace radially outward in the tubular sieve 18, dirt particles largerthan the sieve orifices 21 of the tubular sieve 18 being retained in theinterior of the tubular sieve 18. Thus, only purified fluid passes intothe exterior 22 between the tubular sieve 18 and the tubular body 2. Thefluid passes from there, via the fluid ducts 15, into the inside of thevalve chamber 7.

[0031] The flow, of course, takes place only with the valve open, thatis to say in the switching position in which the valve body 8 lies onthe spherical seat 16 and the passage bore 10 is released.

[0032] A valve 1 according to the invention can easily be built into afluid circuit, for example a refrigerant circuit, which, as aconsequence of manufacture, contains dirt particles which are notcompatible with conventional refrigerant valves and cause malfunctions.

[0033] The use of the valve 1 is aimed at closed fluid circuits whichremain closed after manufacture over the useful life of the valve 1. Thefilter capacity of the filter system consisting of the tubular filter 18and of the magnetic filter 19 must in this case be designed in such away that once-only complete purification of the fluid located in thecircuit, without clogging, can follow.

[0034] In this way, that is to say by the use of a filter 18, 19 in theinflow line 20 of the tubular body 2 and, in particular, by the directarrangement next to the valve chamber 7, an introduction of dirt intothe valve chamber 7 is reliably ruled out to an extent such thatpermanently leaktight and low-wear functioning of the valve 1 can beensured.

[0035]FIG. 2 corresponds essentially to the abovementioned exemplaryembodiment, in this case, by contrast, a second tubular outflow line 23leading into the inside of the tubular body 2 as far as the pole piece 5and being fixed there in a leaktight manner in a corresponding bore 24.The tubular body 2 and the outflow line 23 are closed off relative toone another, for example pressed or soldered, in a leaktight manner at asealing point 25.

[0036] An interspace 26, to which an inflow line 27 is connected, isthus obtained between the outflow line 23 and the tubular body 2. Theinflow line 27 may, for example, be soldered in a corresponding orificeof the tubular body 2.

[0037] In this embodiment, the pole piece 5 also comprises a passagebore 28 connecting the valve chamber 7 to the interspace 26 via thefluid ducts 15.

[0038] The fluid or refrigerant can pass in the direction of the arrow Pinto the interspace 26 and from there through the magnetic filter 19into the in this case annular interior between the tubular sieve 18 andthe outflow line 23. The fluid subsequently flows radially outward intothe exterior 22 between the tubular sieve 18 and the tubular body 2,from where it passes via the fluid ducts 15 into the valve chamber 7.

[0039] The fluid then flows out either via the outflow line 23 or viathe outflow line 11, depending on the switching position of the valvebody 8. In the switching position a illustrated, the passage bore 28 ofthe pole piece 5 is open, that is to say outflow takes place via theoutflow line 23.

[0040] By means of a control pulse from the control coil 3, the valvebody 8 can be brought onto the opposite spherical seat 16, with theresult that the passage bore 28 is closed and the passage bore 10 isopened. In this switching position described, but not illustrated, thefluid flows out via the outflow line 11.

[0041] Instead of the adapter pieces 4 which have a conical outflowsurface inside the control coil 3, in the present case sleeve-shapedflux guide plates 29, which completely fill the interspace between thetubular body 2 and the control coil 3, are provided for guiding themagnetic flux inside the control coil 3. The flux guide plates 29 are ineach case connected to a closing plate 30 which itself is connected towhat are known as yoke plates, not illustrated in any more detail, ormerges into these. The flux guide plates 29 may be punched, bent orwound together with the closing plate 30 and the entire yoke platearrangement, not illustrated in any more detail, out of a flat material.

[0042] List of reference symbols:

[0043]1 Valve

[0044]2 Tubular body

[0045]3 Control coil

[0046]4 Adapter pieces

[0047]5 Pole piece

[0048]6 Pole piece

[0049]7 Valve chamber

[0050]8 Valve body

[0051]9 Spherical seat

[0052]10 Passage bore

[0053]11 Outflow line

[0054]12 Annular magnet

[0055]13 Annular magnet

[0056]14 Spacer ring

[0057]15 Fluid duct

[0058]16 Spherical seat

[0059]17 Step

[0060]18 Tubular sieve

[0061]19 Magnetic filter

[0062]20 Inflow line

[0063]21 Sieve orifice

[0064]22 Exterior

[0065]23 Outflow line

[0066]24 Bore

[0067]25 Sealing point

[0068]26 Interspace

[0069]27 Inflow line

[0070]28 Passage bore

[0071]29 Flux guide plate

[0072]30 Closing plate

What is claimed is:
 1. Bistable electromagnetic valve with a valvechamber arranged between two pole pieces and with a valve body which isdisplaceable therein between two end positions and which is designed asan magnet armature for at least one permanent magnet and for at leastone control coil, characterized in that the valve chamber (7) isarranged within the control coil (3) and the outer wall of the valvechamber (7) is formed within the control coil (3) by a cylindricaltubular body (2) which extends at least beyond the pole pieces (5, 6)inserted into the cylindrical tubular body (2).
 2. Valve according toclaim 1, characterized in that the tubular body extends at least as faras the end faces of the control coil (3).
 3. Valve according to one ofthe abovementioned claims, characterized in that the fluid connections(11, 20) of the valve (1) are formed on the cylindrical tubular body(2).
 4. Valve according to one of the abovementioned claims,characterized in that at least one end of the tubular body (2) forms atubular connection (11, 20) for the fluid.
 11. Method for producing abistable electromagnetic valve with a valve chamber arranged between twopole pieces and with a valve body which is displaceable therein betweentwo end positions and which is designed as a magnet armature for atleast one permanent magnet and for at least one control coil,characterized in that a continuously cylindrical tubular body (2) isused as the outer wall of the valve chamber (7), valve components (5, 6,18) being introduced into the tubular body (2).
 12. Cold-generatingcircuit for a refrigerating system, in particular with a plurality ofrefrigerating spaces, a compressor, a condenser, a plurality ofevaporators which are assigned to at least one of the refrigeratingspaces and at least one electrical control valve for connecting thecondenser to one or more of the evaporators according to predeterminedoperating states, characterized in that the control valve (1) isdesigned according to one of the abovementioned claims.
 13. Domesticappliance with a cold-generating circuit, in particular refrigerator orfreezer, characterized in that a cold-generating circuit having a valveaccording to one of claims 1 to 10 is provided.